Dresden 2009 – wissenschaftliches Programm

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PV: Plenarvorträge

PV I

PV I: Plenarvortrag

Montag, 23. März 2009, 08:30–09:15, HSZ 01

The Ring of Brownian motion: the good, the bad and the simply silly — •Peter Hanggi — University of Augsburg, 86135 Augsburg, Germany

Since the turn of the 20-th century Brownian hiss has continuously disclosed a rich variety of phenomena in and around physics. The understanding of this jittering motion of suspended microscopic particles has undoubtedly helped to reinforce and substantiate those pillars on which the basic modern physical theories are resting: Its formal description provided the key to great achievements in statistical mechanics, the foundations of quantum mechanics and even astrophysical phenomena, to name only a few [1]. – Brownian motion determines the rate limiting step in most transport phenomena via escape events that help to overcome obstructing bottlenecks [2], or triggers oscillatory dynamics in excitable media [3]. Although noise is usually thought of as the enemy of order it in fact also can be of constructive influence. The phenomena of Stochastic Resonance [4,5] and Brownian motors [6,7] present two such archetypes wherein random Brownian dynamics together with unbiased nonequilibrium forces beneficially cooperate in enhancing detection and/or in facilitating directed transmission of information. The applications range from innovative information processing devices in physics, chemistry, and in physical biology to new hardware for medical rehabilitation. Particularly, those additional non-equilibrium disturbances enable the rectification of haphazard Brownian noise so that quantum and classical objects can be directed around on a priori designed routes (Brownian motors). Despite its thrilling manifold successes Brownian motion nevertheless is not the “Theory of Everything”, as is revealed by some more doubtful applications.

[1] W. Ebeling and I. M. Sokolov, Statistical thermodynamics and stochastic theory of nonequilibrium systems, Adv. Stat. Mech. Vol. 8 (World Scientific, Singapore 2005).

[2] P. Hanggi, P. Talkner, and M. Borkovec, Reaction-rate theory: fifty years after Kramers, Rev. Mod. Phys. 62, 251 (1990).

[3] B. Lindner, J. Garcia-Ojalvo, A. Neiman and L. Schimansky-Geier, Effects of noise in excitable systems, Phys. Rep. 392, 321 (2004).

[4] L. Gammaitoni, P. Hanggi, P. Jung and F. Marchesoni, Stochastic Resonance, Rev. Mod.Phys. 70, 223 (1998).

[5] P. Hanggi, Stochastic Resonance in Physics and Biology, ChemPhysChem 3, 285 (2002).

[6] R. D. Astumian and P. Hanggi, Brownian motors, Physics Today 55 (11), 33 (2002).

[7] P. Hanggi and F. Marchesoni, Artificial Brownian motors: Controlling transport on the nanoscale, Rev. Mod. Phys. (2009), arXiv:0807.1283